Coal handling system



Oct. 30, 1951 P. L. BETZ ET AL I 2,573,535

COAL HANDLING SYSTEM Filed Feb. 6, 1946 w INVENTORS P J. (1

dHon-zegs Patented Oct. 30, 1951 COAL ND GSYS E Paul; L. Betz, ltim Md; .a. L. .eba;st-i 3! l gapre washin -gjgo D. 0., assignors to Conso i e s. E ctr h and: Few r; ome- B l o 'Ba i tinniq Ma yland.

r metey. Md; a; eqmqmz Application Febrfiany; 6, 1946, Serial Np. 645,864

Ellis n elm-1 v tem-fies o s e mse heind e coal in' powenplentsendm xe e lc ieu-le y floeue systemswh e n oal s. m lied'fwv fi eemi or sigqkers from eleva tedsgo age spaces 7 n meder n we enfim he ,uninfifi fk (391136615X of'c alz f om file-51 1%? unkexs o: l pulver z ns: m lls n s ke s ie Q ereet mee -tenee-s pnaet ee, QWQVQ 's z l; stoppa e e l ellt' result; usuallyrom excessivetme emre nfi e-eq an on eeesiqn e vsu he at e astq-n ult i a low rin .of he ouipu of he st er The r sent. nven e s n e ded 9. mi mi v sue s page -s I I v Inna-any cemmm efien. newe r leete the leaves the storage bunker by gravity angi; passes; into. st e hutes emer er ee ee i ne a e whic onvem eoe1 os-st e pul zinemm; q etelser hea ed: at; owen eve them the; e ee ev l l eiehuees areenp ee l efns de ab n ths sineeihey muete t-e d. fr m h un er,- loca e near; he oefio the p er le m t e in fleerw i-the eiler, nea t eneund e elhen the IPQEWUEQ on-.te te the' el: is w i t fir: m s e eri nce th such; m, W t eer ee sl me etur l on ent; w ve eommqn; d 1 1 1015 1 1 5 an ne allwhe ekeflerei Q0941: v eed welfl s mae ntflm d: with considerable dimgulty it often beingngqes exmo s nt tem nuelm ho s: t r, o neemi he seiekinezqi; 111 9 11 i the bunker a d: in he U qhutes.

he; e ei av ty fe d s s em eretof r known, the chutes deliver the coal to a; feeding de ces oca d. mm iate y adja e he ulverzi e-mill- 1 5 1,1} su a n eme e en re.- chu e sbetween the bunkenand the feederi nqr s melly' mp e e y l ee w h, l; n the nly ieeele ien hefl W= of a thr ug e system;

eentr enq z h ee ers:- C mer ye the e e 0fl move ent is: relevtiv zeelMh Qss eet enmea of t e chut s.

e a i y e vs e ler to uret ei mes a e; QL eee e en ine otalneneie e e o. n t a it; fifiq e 1W5? Fo ex elz -le.v n; a miee ent l: tetiem e e e 121mb o t e ey ten ders e beqz, the. m lt l ei-ty s. n the ndeno 02: 299% 29, seeend he; 1QSs=$$3 Qn@le Ie@ of? he: Eh-we s; bo t Site 1 1 1 e/ em. and; the eta z quantity of coal in transit at any instantisa pgqximately Stons. I

21 1 1 t i 6 11 he n serita nv neienl.

4, e de a d m reve sbem; hemel ine w i p wewl n swhe ei t e chu re;

hieh; vele e tex emh ein he. el is ed 9 th ar e 2 ne exime ly he ame reteas, t s: deliver-.1291 tgsthe ,pglvepizing mill or stoker.

n h r eba'eet. i ro e. o e e! h ns line i the; qheree en de r, ecl;w in:

' he: e ki x- Q11. we l-meme hx ugh he chutes a m! nstan is Preme wme l: n compar ons ith. s e zhe eby abl si he use f: ub an iall ghten, mere flexi e chute on:- ue ienbieet si e ev qe; imle qve eeel; del e w eeelir m isellfi me ee y ene trolled so as t prevenj', flgogl ipgfoncl o lging qf the system en wla-ie ide eilesl he a en: 9e et e v he stem; i 'ee e n e he chutes: e e me x em tyfefieee hese ende hesriebiee e ap e r.- m eg u m ween. eneide etien he deifl eds qe er p e efi e i'te eev bed me es. 1E t nv e whi h el we- In this; CQQQQ iPBQ e hheugh. h ee w e fie lly dif e ones o eq l. aml eg s stems r id se i e ee .d be; e; w ens ed; c ms. 1 ew; he d r v in whe ein l kesdsi eeer-likezp lt-es amu h F s L, i sehem tie; eva ions}; v ew o o e; iqem ofe eekha d lin syst m mbeelm mepree nt ma neie .5

B as 2 anew; e te, sim le w i ws nen e mi emodifica ions; rfv hel'syetem shown n; E -s n the c0a de1iveIX-S3ESW I lust at d n His 3. thefre er nee numeral H; indiqa es a. porti n Qfs? n. elev ted; stora e: bnnke e w ich is. deleted,- tepp yal-s to; as nulw e -ing mill: 1:2 he atter bein proyided. with uel feedin outlets o tubes: wrthmu h; which; pulverized; coal; and ainpess 01.1.,

their Way to: the; boil r; burners (notes shownk,

Th -bunker k has a pair ofiutlet A; each: of: hich/ s: adapted: to; co vey coal: to a. feed n de..-

ice. I 5 hie rx ye x nlan suitabl en relle e anne as by: electric-s motor; l6;-v The feeders; '15 m y beef: any f LBhBWEHr-KHOWII. screw, e:

miee e'e a belt, star. onrota y d s es. and m ybe of; theeensimuct-ion iliusbnated inx opend-m n gee l eekiqn see el-Nm.fiQfi Qfi hfiQW Ea ene m. 5 2 12 5, dated:- Novemlqer -'-7;,-s1: 0; which pr vides;

a pgqssung seal betweenxthe atmosphez q and. the;

chute ystemn xttobedescribed:

nemelly qnly err elly fi lleiwithieqelsmewn ej; as Tnef eders i5ifiupp yic0 rl .to the-up rds f a pair of subsidiary chutes I! which connect at their lower ends with a main chute I8, the latte. in turn having its outlet end connected to the to; of a hopper I9 located closely adjacent the pulverizing mill I2. The bottom of hopper I9 feeds directly into another feeding device 20 which is controllably' driven in the same manner as chute feeders I5, as by an electric motor 2 I, and delivers coal to the mill I2 in known manner. feeder 20 may be of any desired construction-and is usually a component part of the pulverizing mill, the structural details of which form nopart of the present invention.

The drive motors I6 and 2I of chute feeders I5 and mill feeder 29 are provided with suitable electrical supply circuits 22 and 23, respectively,

which are connected to themain'supplyfline .24

2 sufficient to compensate for brief periods of decreased flow of 'coal through the chutes I1 and I8, "such as may be caused by slowing down of feeders I5 or failure of the coal to discharge properly fromthe bunker II.

"Hopper I9 is also provided with automatic control means for stopping, or reducing the speedof, the motors I6whichdrive the chute feeders I5 in the event that coal is supplied to the hopper faster than it is delivered therefrom to the pulverizer I2 by feeder 20, and the level ofthe coal in the hopper rises above a predetermined point. As shown diagrammatically in the embodiment illustrated, hopper I9 is pro"- vided with a coal-level responsive switch means 26 which is connected by leads 2! to a relay 28, the latter being interposed between the supply lines 22 for the motors I6 and the switch 25 in the main supply-line 24.- Any suitable level responsiveswitch may be used at 26.- -Several such switches are available commercially, one employing a tubular mercury switch that responds tothe pre'ssure of the coal against a relatively movable portion of the side wall of the hopper. A suitable level responsive switch is also shown inI-Iayes-Patent No. 2,429,159, granted October 14, 1947. In the event that the level of the coal ployed and the speed of motors I6 is tobe re duced'upon actuation of level responsive switch 26, relay 28'would transfer the circuit connections' of the-motor so as to increase the number ofpoles in the motor,-and where direct currentis used; relay 28 would operate to decrease the voltage applied to the armature as-by inserting a resistance inseries with the armature circuit or to increase the field current as by shunt- The mill" .1

4 ing a resistance in the field circuit. The location of switch means 26 in hoper I9 is preferably such that the storage space in the hopper above the switch is at least equal in volume to the volume of coal normally contained in the subsidiary and main" chute members I1 and ;IB so that when the, entire system is shutdown by opening main switch 25, space will be available for receiving all of the coal then in transit in the chute system. In order to assist in effecting a uniform flow of coal from bunker II through outlets I4 and into chute feeders I5, the bunker may be equipped with suitable means, indicated at 29,

,for positively assisting in emptying the bunker. For example, the bunker emptying means 29 may comprise devices for vibrating the walls of the .bunker, several forms of which are available commercially. One commercial device suitable 26, -just as in the system of Fig. 1.

Where desirable, another coal-level switch" for this purpose employs an electromagnet that is operated on alternating current. Another device'employs a motor with a relatively large'unbalanced weight that produces the desired vibration. A suitable device for this purpose is also disclosed in Francis Patent No. 2,276,382, granted March 1'7, 1945. The bunker emptying means 29 may be operated either continuously during operation of the entire system, or intermittently as dictated by the coal flow conditions existing in the chute'feeders I5 or chutes I1 and I8. In the latter case, proper operation may be insured by installing electrical contacting devices (not shown) in feeders I5 or chutes I1 and I8 which are responsive to the movement of coal for controlling energization of bunker emptying pair of subsidiary chutes 30 the lower ends of which are connected to'the inlet of a chute feeder 3|, the latter being driven in any suitable manner, as by an electric motor 32. The supply circuit 33 of motor 32 is connected to'the main supply line 24 through a relay 28, which is in turn actuated by a coal-level responsive switch (not shown in the drawing) may be installed in hopper I9 at a lower level than switch 26 to set the lower limit to which the coal level may fall.

Actuation of this switch due to low'coal levelcauses relay 28 to increase the rate of feed of chute feeders I5 in Fig. 1 and chute feeder'3lin Fig. 2, thereby building up the quantity of coal stored in hopper I9." Where the speed of the feeder motors is to be increased on operation of the low level responsive switch relay means would be provided in the circuit of motors I6 or 32 to' resistance of the-field circuit. The coal in 'hop--' per I9 also serves as a pressure sealing column where non-pressure sealing chute feeders are employed. 1

The chute feeder 31 is normally driven by the motor 32 at a speed such as to deliver coal to the main chute I8 at a rate approximately equal to' that at which the mill feeder 20 withdraws coal from-the hopper I9. Since in this embodi ment of the. invention thesubsidiarychutes, 3t arernormally. solidly filled with. coal, said chutes may beiprovidedif desired, with vibrators or other suitable means 34 which, together with bunker emptying means 29, insure a steady flow. ofwcoalfito. chutefeeder 31. Asin the case of bunker emptying. means. 29,-, chute. emptyin means 34 maybe. operated eitherintermittently,

whenever the flow ofcoal feeder 3! is interrupted,

or continuouslyduring the operation of said feeder.

In the embodiments of the invention illustrated i-n-Eigs. -1 and2, vboth chute, feeders and mill feeders are. employed,sthe former controlling the rate oi -feed of-coal into. the. chute. system, and the.. latter controlling the rate, of discharge of coal fromuthe. storage hopper associated with the outletof the main. chute, The arrangement showniin Eig. 3 employs chute feeders. only, and omits the. storage hopper and mill feederof the othentwo forms of the invention. vAs. shownin Fig. 3, the chute. feeders 3.5.regulate the iioivof coal into subsidiary chutes l1- wln'ch in. turn feed themain chute l8, just as in the case of 1. Chute feeders 35 are. of the pressure. sealingtype and are preferably of the construc: tion illustrated in the aforesaid Patent No. 2,529,445, and may be driven in any suitable mannen-as by electricomotors. 3.5.. The use of pressure-sealing chute feeders 35 is necessary as otherwise the proper pressure could notbe maintained within chutes H; and l8.and in pulverizing mill l2 Theumain chute i8. delivers coal die rectly into pulverizingmill 12, the rateof coal flow being controlled solely by. thefeeding rate ofthe feeders 35. Since. only. a relatively small amountofcoal is involved, the mill {-2 would normally provide sufficient storage capacity to accommodate all of the coal in transit in the chute system when operationuofafeeders 35 is discontinued. -If desired, however, a small hopper (notshown) may be installed between the outletof chute 8 and pulverizing-mil-l 52 in order. to'provide additional storage capacity. Thereis thus. provided by the present invention a coalhandling system wherein, whenthe sys.-. tem is not in operation, the chutes are normally empty of coal.- "In order to put the. system into operation, the switch 25. in the main supply line is closedso as to start the mill and/or chute feeders; and-since coal is fed to. an initially empty chute at approximately the same rate that it leaves-the chute, no acou-mu-lationof coal takes place'in the chute and the. chute runs only par: tiall y'filled even when operating at full load. By positioning the chute feeders adjacent the storage bunkerand inclining the chutes at suitableangles approaching the vertical, high velocity coal flow through only partially filled chutes is obtained, in direct contrast with the older systerns wherein the only feeders employed are adjacent the pulverizingmill and'the chute system is completely filled with coal'moving at an extremely low velocity. For example, in systems employing the present invention, the average coal velocity is measured in feet, rather than hundredthsbf a foot, per second, and the total quantity. of-coal in the chute system at anyv instant maybe as little as 10. pounds, as compared with 8 tons in the older types of system. Figs. 1, 2 and 3 indicate .the'application of the present invention to. new chute construction. The invention is equally applicable, however, to existing chute installations which, while. of enormously excessive capacity as far as the requirements of the r ent, invention are o cerned, will, neverthele s. pe form sati faotorilr when adapted-101:; use i acco dance. withthe fore in disc osu es i. 1

An th r advanta e of t e pre ent; inven ion residessin, the. fact. that, whereas I tho ohutes prior syst ms are; o ma sive oon tiuoti nre: quirin weld d on r veted; ee p ate. wa a mem. ts torsupporti he. t n of oa Whichsoli y fill hochutes; hechutes mplo ed in. sy tems embodyin the presen in ention. onta n on y; a few ounds otcoal a d eed not beef.- la e cl'flssr'figctifi fl areas hochutes e co structed of st elr in or of relat izely f ex ble tubules members. The use. f ma l diameter pipes for chutesisof advan a e. n, that it mits theready subst tut on of en emntr ch te for one which m y hav become obst ucted due to. the lodging of-.foro snbodie there m-am also, increases the. as with. whioh tr otural members..-in.the power pl n m y beav i ed whenpositioning the. chutes While-three. specifically differ nt. coa ha dl n systems. embodyin the invention have been ole: scribed and. illustrated in the ac ompanyin drawing, it will be. obvious that the invention is. not limited ta he particular arran ementsshown, b i a l of. a. v rie y of mechanical. ems odim ts- .F'or er -1111 16,. while t invention hasheen described, in association bunker means having two outlets per. pulveri zingnmill, it isto be understood th t it is equally pp i abl o any ot er: form of: coal stora e e ns such; asbins, silos. and the like, having one; outlet p .pulverizing mill. It. will alsobe. reco nized that. although. examples have been iven of; specific types of feedersvibrators, and-otherele mentssuitable for use in thesystemof the present invention, the specific construction-fthese devices is not" essential to the inventive concept and that various. equivalent means are a eptable in the overall combination. Var-iousother changes which will nowsuggest themselves to those skilled in the. art may be,

.- made. in the form, details, of construction and;

' means relatively. remote from said device, a store.

age hopper adjacentsaid device, a chute. adapted to receive coal from said storage means and dc: liver. it to said storage-hopper,. the lower end of said chute beingopen and unobstructed and de.--. livering coal directly into said hopper, said hope pe'r having an outlet at its lower end. connected, to said device through which coal is dischargedfrom the hopper by gravity, whereby the coal in s'aid'ihopper. is adapted to. serveas a seal between the air pressures existing in said device and in the space above the level of the. coal in. said hopper, means for feeding coal from said storage. means to the uppenend of said chute, and motormeans for driving said feeding means at different rates of: feed, said storage hopper having a, volume. at least sufiicientto accommodate allzof the coal in transit insaid chute at the maximum feeding rate. of said feeding means in additionito. the coal in said hopper whenoperation of said: motonmea'ns is discontinued.

2. In a coal handling system for power plants adapted to deliver coal continuously to acoal receiving device such as a pulverizing mill,-the combination therewith of an elevated coal storage means relatively remote from said device, a storagehopper adjacent said device, a steeply inclined chute adapted to receive coal from said storage means and deliver it to said storage hopper, the lower end of said chute being open and unobstructed and delivering coal directly into said hopper, said hopper having an outlet at its lower end connected to said device through which coal is discharged from the hopper by gravity, whereby the coal in said hopper'is adapted to serve as a seal between the air pressures existing in said device and in the space above the level of the coal in said hopper, means for feeding coal from said storage means to the upper end of said chute, motor means for driving said feeding means at different rates of feed, and means for so controlling said motor means that coal is fed into'said chute at approximately the same rate as that at which it is deliveredthereby'into said hopper, whereby the chute is normally only partially filled with coal when the system is in operation, said storage hopper having a. volume at least sufiicient to accommodate all of the coal in transit in-said chute at the maximum feeding rate of said feeding means in addition to the coal in said hopper 'when operation of said motor means is discontinued.

3. 'In a coal handling system for power plants adapted to deliver coal continuously to a coal receiving device such as a pulverizing mill, the combination therewith 'of an elevated coal storage means relativelyremote from said device, a

storage hopper adjacent said device, a chute adapted to receive coal from said storage means and deliver it to said storage hopper, the lower end of'said chute being open and unobstructed and delivering coal directly into said hopper, said hopper having an outlet at its lower end connected to said device through which coal is discharged from the hopper by gravity, whereby the coal in said hopper is adapted to serve as a seal between the air pressures existing in said device and in the space above the level of the coal in said hopper, motor driven means for feeding coal from said storage means to the upper end of said chute, continuously operable motor driven means for feeding coal from the outlet of said hopperto 'said'device, and means responsive to the amount of coal in said hopper for so controlling the relative speeds of operation of said motor driven feed-' ing means that coal .is fed from said storage means to said chute at approximately the same rate as "that at which it isfed from said'hopper to said device, said hopper having a volume at least suflicient to accommodate all of the coal in transit in said chute at the maximum feeding rate of said first named feeding means in addition to the coal in said hopper when operation of said means is discontinued.

4. A coal handling system as defined in claim 3 wherein the chute is steeply inclined and of such diameter in relation to the feeding rate of said first named'feeding means that the chute is normally only partially filled with coal when the sys-.

outlet connected to the latter forthe delivery of coal thereto, a chute adapted to receive coal from said storage means and deliver it to said storage hopper, the lower end of said chute being open and unobstructed and delivering coal directly into said hopper, motor driven means for feeding coal from said storage means to the upper end of said chute, continuously operable motor driven means for feeding coal from the outlet of said hopper to said device, and relay means including a switch responsive to the level of the coal in said hopper for so controlling the speed of operation of said first named feeding means that coal is fed thereby from said storage means to said chute at approximately the same rate as that at which it is fed by said second named feeding means from said hopper to said device, the volume of said hopper above the level of said switch beingat least sufficient to accommodate all oflthe coal in transit in said chute atthe maximum feeding rate of said first named feeding means when operation of said means is discontinued.

6. In a-coal handling system for power plants adapted to deliver coal continuously to a coal receiving device such as a pulverizing mill, the combination therewith of an elevated coal storage means relatively remote from said device, a storage hopper adjacent said device, a chute adapted to receive coal from said storage means and deliver it to said storage hopper, the lower.

end of said chute being open and unobstructed and delivering coal directly into said hopper, said hopper having an outlet at its lower end connected to said device through which coal is discharged from the hopper by gravity, whereby the coal in said hopper is adapted to serve as a seal between the air pressures existing in said device'and. in the space above the level of the coal in said hopper, motor driven means for feeding coal from said storage means to the upper end of said chute. continuously operable motor driven means for feeding coal from the outlet of said hopper to said device, and control means responsive to variations in the level of the coal in said hopper with refer-v ence to a predetermined level for so controlling the operation of said first named feeding means that coal is fed thereby from said storage means to said chute at approximately the same rate as that at which it is fed by said second named feeding means from said hopper to said device, the volume of said hopper above said predetermined level being at least sufficient to accommodate all of the coal in transit in said chute at the maximum feeding rate of said first named feeding means when operation of said means is discontinued.

PAUL L. BETZ. SEBASTIAN KARRER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 327,210 Westlake Sept. 29, 1885 421,556 Cooley Feb. 18, 1890 952,266 Mann Mar. 10, 1910 1,301,978 Schafier Apr. 29, 1919 1,640,770 Hamilton Aug. 30, 1927 1,942,166 Gisser Jan. 2, 1934 2,276,382 Francis Mar. 17, 1945 2,381,505 Lindholm Aug. '7, 1945 2,408,221 Michel Sept. 24, 1946 

